Osteoprotogerin (OPG) and the receptor activators of nuclear factor-kβ (RANK) and nuclear factor-kβ ligand (RANKL) play an important role in bone metabolism. RANKL binds to RANK, which is expressed by osteoclasts, whereas OPG acts as its decoy receptor, blocking the RANKRANKL interaction.

In conclusion, although endogenous hyperthyroidism increases the levels of bone formation and resorption markers, no change is observed in the serum levels of osteoporosis-associated cytokines, RANKL and OPG.